Telephone ringer



@CL 10, 19 7 J. 5. P. ROBERTON ETAL 6 58 TELEPHONE RINGER 2 Sheets-Sheet1 Filed May 18, 1965 Oct. 10, 1967 J. S. P. ROBERTON ETAL TELEPHONERINGER 2 sheets-sheet 2 Filed May 18, 1965 United. States Patent3,346,858 TELEPHONE RINGER James Samuel Paterson Roberton, Leslie EugeneBasil Dymoke-Brad'shaw, and Nirmal Singh Lotay, London, England,assignors to International Standard Electric Corporation, New York,N.Y., a corporation of Delaware Filed May 18, 1965, Ser. No. 456,702Claims priority, application Great Britain, June 8, 1964 23,592/64 9Claims. (Cl. 340-397) ABSTRACT OF THE DISCLOSURE A single coil telephoneringer wherein the coil has a permanent magnet core with pole piecesprojecting beyond the ends of the coil. A U-shaped armature is pivotedabout half way along the length of the coil. The cooperating pole piecesand armature ends are angled to enhance the magnetic moment. The volumeof the ring is controlled 'using a formed wheel arrangement for clampingthe bell hammer.

This invention relates to a polarised magnetic device, such as a ringer,as used in a telephone subscribers instrument.

According to the present invention there is provided a polarisedmagnetic device, which comprises a magnetisable core surrounded by anenergising coil, end portions of said core projecting out of said coil,an armature of generally U shaped construction mounted so that the baseportion of the U is generally parallel to said core, said armature beingrockable about a pivoted axis between the ends of said base portion, endportions of the legs of said U-shaped portion which co-operate with theend portions of said core, and a source of magnetic flux which impartsmagnetisation of the same sense to the faces of the end portions of thecore which co-operate with the end portions of said armature, so thatenergisation of the coil with alternating current causes said armatureto rock about its pivots, the end portions of the armature and the facesof the pole ends of said core which co-operate with said armature end=p0rti0ns being at an angle to the length of said core. I

An embodiment of the invention will now be described with reference tothe accompanying drawings, in which:

FIG. 1 is a side view of a ringer according to the invention.

FIG. 2 is a plan view of the ringer of FIG. 1, the arrow I indicatingthe direction from which it is seen in FIG. 1.

FIG. 3 is a section of the armature pivot of the ringer of FIG. 1.

FIG. 4 shows the arrangement of the armature securing spring.

FIG. 5 is a side view and a cross-section of an alternative form ofvolume control wheel.

FIG. 6 is an alternative form of ringer frame to that of FIG. 1.

Referring first to FIGS. 1 and 2, the ringer includes a coil-carryingspool 1 on a ferrite magnet 2, polarised to have one longitudinal face anorth pole and the other longitudinal face a south pole. The alternatingcurrent through the coil therefore sets up magnetic fields whichalternately reinforce or diminish the field of the permanent magnet inan opposite manner at each pole. There is also a soft iron core 3. Itshould be noted that the ringer has one coil only, which simplifiesconstruction. An armature 4 is pivoted at 5, 6 on a platform 7 providedby an upstanding portion of a base plate 8. The pivots may, for example,be ball bearings or rollers held captive in recesses in the armature andthe platform, as shown in FIG. 3. Alternatively each pivot can be aridge on the inside of the armature which engages with an indentation onthe platform or vice versa. Again, domeheaded rivets on the platform orthe armature and held captive in recesses on the armature or platformrespectively could be used. The pivots are held in place (where they areballs or rollers) and the armature retained in position by a formed clipspring 9 bearing against the outer surface of the armature 4. A centralportion of the spring passes through a hole in the armature 4 and isheld in a cruciform slot and recess in the platform 7, as shown in FIG.4.

As can be seen from FIG. 4, the slot is larger in the longitudinal thanin the vertical sense. The spring is mounted by pushing its right handend (FIG. 4) through the longer slot and then turning it through so thatit reaches the position shown in FIG. 4. This, with the cutaway portionsin the thickness of the portion 7 ensures that the spring positivelyretains the armature; hence it will not wobble as wear occurs in use.

When the coil is energised by an alternating current, the core 11 ismagnetised, and its magnetisation direction is reversed on every halfcycle. The armature whose ends thus alternate in polarity between northand south polarisation co-operates with the steady polarity flux fromthe permanent magnet, such that the armature rocks about its pivot, therocking occurring in a plane perpendicular to the axis through thepivots. The flux of the permanent magnet tends to bias the armature byacting to polarize the armature. The magnetic bias causes the armatureto react faster to the alternating current generated flux. The endportions 10, 11 (FIG. 2) of the armature and of the core are angled sothat the direction of the magnetic force acting on each end pole face ofthe armature is perpendicular to the line from the pivot to that end.Hence the force has a maximum moment about the pivot. The armature isshown as having its pole ends sharply angled, but if this isinconvenient, for example for production reasons, it would be possiblefor the junction between the end portion and the legs of the armature tobe curved.

Referring again to FIGS. 1 and 2, a hammer 12 is carried by thearmature, and when the armature rocks, the hammer strikes two gongs (notshown), one on each side of the hammer head.

The volume of sound emitted by the bell can be controlled by a wheel 13mounted beneath the hammer so that the arm of the hammer floats in achannel around the circumference of the wheel. This channel has avariable width, as shown in FIG. 2, and rotation of the wheel causes thewalls of the channel to converge or diverge from the arm, controllingthe distance the arm of the hammer can move sideways, and hence theforce with which it hits the gongs. The arm of the hammer is, of course,flexible.

An alternative form of volume control wheel is shown in FIG. 5. Thiswheel is an eccentric and its circumferential channel is lined with adamping material such as a foam rubber or plastics material. Rotation ofthe wheel when mounted beneath the arm of the hammer causes the foamrubber lining mentioned above to bear on the arm. This exerts a dampingaction on the arm, lessening the force with which the head of the hammerstrikes the gongs.

In FIG. 1 the volume control wheel is shown axially supported betweentwo bent-up portions of the base plate. Another method of supporting thewheel is shown in FIG. 6, where a composite moulding provides an axialsupport. The plastics wheel with an integral axle is pressed into thecylindrical bearings. The walls of the bearings move apart allowingentry and finally snap inwards, partially embracing and securing theaxle. This method of Patented Oct. 10, 1967 insertion of the axle isshown in the inset to FIG. 6'. During adjustment of the volume control,an upward force is exerted on the axle which tends to push it out of itsbearings. The axle remains secured, however, as the moulding is screwedfirmly to the base plate, thus preventing the walls from flexingoutwards.

Reverting to FIG. 2, the spool unit is secured to its base plate by twoscrews 14 (FIG. 2) which enter slots 15 at the sides of the spool checksand engage in two threaded holes in the base plate. Adjustment of theairgaps is made by slackening off these screws and sliding the spooltogether with the magnet and core towards or away from the armature.Slots are also provided on the spool unit in the alternativeconstruction of FIG. 6, as indicated at 15'.

It is to be understood that the foregoing description of specificexamples of this invention is made by way of example only and is not tobe considered as a limitation on its scope.

What we claim is:

1. A polarized magnetic ringing device having at least one gong, saiddevice comprising a magnetizable core surrounded by an energizing coil,end portions of said core projecting out of said coil to form polepieces, an armature of generally U-shaped construction with the baseportion of the U-shape normally parallel to said core, said armaturebeing rockable about a pivotal axis located between the ends of saidbase portion, end portions of the legs of said U-shaped armaturecooperatively associated with the pole pieces, arm and hammer meansattached to said armature in a position normal to the length of saidcore and juxtaposed with said hammer to said gong, permanent magnetmeans for imparting magnetization of the same sense to the faces of eachof the pole pieces, so that energization of the coil with alternatingcurrent causes the said armature to rock about the pivotal axis, and theend portions of the armature and the faces of the pole pieces beingparallel to each other and at an obtuse angle to the length of the core.

2. A polarised magnetic device as claimed in claim 1, wherein saidarmature ends and pole pieces lie respectively along and parallel to theline from said pivotal axis to the ends of the armature.

3. A device as claimed in claim 2, and in which said pivotal ax isaboutwhich the armature rocks is defined by a plurality of balls or rollers,each of which is held captive in recesses in said armature and in asupport therefor.

4. A device as claimed in claim 2, and in which said pivoted axis aboutwhich the armature rocks is defined by ridges on the armature located inindentations in a support for the armature, or vice versa.

5. A device as claimed in claim 4, wherein said armature is held inplace by a formed clip spring bearing against the opposite surface ofthe armature from that on which the pivots lie.

6. The ringing device as claimed in claim 5' including means forsecuring said formed clip spring, said securing means comprising acruciform slot and recess in the base of said ringing device, abutmentmeans in said armature lying directly over said slot, whereby a centralportion of said spring passes through said abutment and is secured in asaid cruciform slot and recess.

7. A device as claimed in claim 1 wherein arm means for carrying ahammer are attached to said armature and wherein control means mountedbeneath the arm of the hammer comprise rotatable means to adjust theforce with which the hammer strikes the gong and hence the volume of thesound emitted.

8. A device as claimed in claim 7, inwhich said control means is a wheelhaving a circumferential channel of varying width in which the arm ofthe hammer floats, rotation of said wheel causing the walls of thechannel to converge on or diverge from the arm, whereby the distancetravelled by the arm and hence the force with which the hammer strikesthe gong or gongs is controllable.

9. A device as claimed in claim 7, in which said control means is aneccentric wheel having a circumferential channel lined with a dampingmaterial such as foam rubber, rotation of said wheel causing the liningto bear on the arm of the hammer, whereby a damping force is appliedthereto which reduces the force with which the hammer strikes the gong.

References Cited UNITED STATES PATENTS 787,936 4/ 1905 North 340-397880,940 3/ 1908 Wagner 340-397 2,733,435 1/1956 Bredehoft 340-402 X2,782,410 2/1957 Alexandersson et al. 340-401 X 2,872,672 2/ 1959 Lucas340-402 X 2,890,447 6/1959 Lohs et al 340-401 X 2,893,001 6/1959 Ham340-392 2,972,139 2/ 1961 Knutson 340-392 3,076,960 2/ 1963 Knutson340-392 3,121,194 2/1964 Stehlik 340-397 X NEIL C. READ, PrimaryExaminer.

THOMAS A. ROBINSON, Examiner.

I. J. LEVIN, Assistant Examiner.

1. A POLARIZED MAGNETIC RINGING DEVICE HAVING AT LEAST ONE GONG, SAIDDEVICE COMPRISING A MAGNETISABLE CORE SURROUNDED BY AN ENERGIZING COIL,END PORTIONS OF SAID CORE PROJECTING OUT OF SAID COIL TO FORM POLEPICES, AN ARMATURE OF GENERALLY U-SHAPED CONSTRUCTION WITH THE BASEPORTION OF THE U-SHAPED NORMALLY PARALLEL TO SAID CORE, SAID ARMATUREBEING ROCKABLE ABOUT A PIVOTAL AXIS LOCATED BETWEEN THE ENDS OF SAIDBASE PORTION, END PORTIONS OF THE LEGS OF SAID U-SHAPED ARMATURECOOPERATIVELY ASSOCIATED WITH THE POLE PIECES, ARM AND HAMMER MEANSATTACHED TO SAID ARMATURE IN A POSITION NORMAL TO THE LENGTH OF SAIDCORE AND JUXTAPOSED WITH SAID HAMMER TO SAID GONG, PERMANENT MAGNETMEANS FOR IMPARTING MAGNETIZATION OF THE SAME SENSE TO THE FACES OF EACHOF THE POLE PIECES, SO THAT ENERGIZATION OF THE COIL WITH ALTERNATINGCURRENT CAUSES THE SAID ARMATURE TO ROCK ABOUT THE PIVOTAL AXIS, AND THEEND PORTIONS OF THE ARMATURE AND THE FACES OF THE POLE PIECES BEINGPARALLEL TO EACH OTHER AND AT AN OBTUSE ANGLE TO THE LENGTH OF THE CORE.